This invention relates to a magnetic head which records in and reads out of a magnetic memory medium and, more particularly to a magnetic head used in a perpendicular magnetic recording system which records a plane magnetic recording medium having an axis of easy magnetization vertical to the plane with a vertical magnetic field component.
Perpendicular magnetic recording systems like the one mentioned above and longitudinal recording systems represent currently available magnetic recording systems. The longitudinal recording system has been theoretically proven to have a limitation in high density recording; see S. Iwasaki, Gakkai Jiki Kiroku Kenkyu Shiryo MR 72 - 7 (1972) and S. Iwasaki and K. Takamura, IEEE Trans. On Magn. MAG - 11, No. 5, pp. 1173-1175 (1980).
In recent years research and development activities have concentrated on the perpendicular magnetic recording system which is a recording system for magnetization vertical to the plane of the recording medium and is suitable for high density recording.
A conventional magnetic head will be described with reference to the first of the attached Figures. FIG. 1 is a perspective view of the structure of a prior art magnetic head used in a perpendicular magnetic recording system. The prior art magnetic head comprises a main pole 3 supported by a support 2 which vertically contacts the surface of a magnetic recording medium 1 and an auxiliary pole 5 having a coil 4 on the outer periphery which does not contact the magnetic recording medium.
Main pole 3 directly contacts the magnetic recording medium and generally comprises a thin film of a magnetic soft metal, such as Permalloy, Alperm, Sendust or Borocube, and a support 2 for protecting the thin film which is made of thermoplastic resin, thermosetting resin or alumina ceramic.
Auxiliary pole 5 is disposed opposite to the main pole 3 via the magnetic recording medium and is frequently made of sintered manganese-zinc-ferrite. Although this auxiliary pole 5 should not directly contact the magnetic recording medium 1, it is preferable in design to arrange the pole 5 as close as possible to the medium 1 for convenience in recording and reproduction. This necessitates a minute gap between the auxiliary pole 5 and the magnetic recording medium 1, but if such a gap is provided due to the deflection and strain on the recording medium 1, or an uneven thickness of an individual recording medium 1, the auxiliary pole 5 is likely to contact the recording medium 1, thus presenting a problem.